Manufacture of plate-glass.



F. L. 0. WADSWORTH.- MANUPACTURE OF PLATE GLASS. APPLIOATION FILED JULY 14, 1905.

Patented Mar. 15, 1910.

2 SHEETS-SHEET 2.

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WITNESSES NVENTOR I GM vl 'tmiren scrarrns PgEN O FRANK L. O. WNADSW'OETH, OF MORGANTOWN, WEST "JIRGINIA, ASSIGNOR TO PIBSSEI) PRISM PLATE GLASS COMPANY, OF NEW YORK, N. Y., A CORPORATION DF WEST VIRGINIA.'

Speeifieation of Letters Patent.

MANIFACTURE OF PLATE-GLASS.

Patented Mar 15, 1910 Application filed July 14, 1905. Serial No. 269,(325.

To (IZZ whom 'it may concern:

Be it known that l FRANK L. O. XVADsi rapid ahstraction of heat froni the glass wom'n, ot Morgantown, Monongalia County,

West Virginia, have invented a new and usetul Improvement in the ll'anufacture ot Plate-Glass, of which the following is a tull,

clear, and exact description, reference being had to the accompanying drawings, torn'ing part of this speeification, in which- Figure 1 is a side elevation of a machine adapted tor practice of my invention; Fig.

2 is a vertical cross-section on the line 11-11 of Fig. 1,; Fig. 3 is a vertical cross-section on the line III-HI of Fig. 1; Fig. l represents ncans which l enploy tor imparting to the die a slight oscillatory motion during' the operation of pressing; Fig. 5 represents a longitudinal central section ot a modified 'form of apparatus tor the practice of my invention: Fig. G an end View of the same: and Fg. 7 is another modification.

In the nanutaeture of plate glass as ordinarily practice& a body of plastic glass is rolled into sheet form on an iron table, and

after annealing is around and polishcd. The quality ot' the plate can be improved by pressing its surface with a die a'ter the glass has been rolled and before it has become chilled and Such pressing will compact the glass, render it dense and diminish the size of 'any bubbles or cavities that it -niay contain, and by giving to the sides of the sheet truer plane surt'aces than can be imparted by rollingr it lessens greatly the amount of grinding which must be done in the final stage of the manutacture, and enables good plates ot quality sufiicient for many purposes to be obtained without grindin and' polishing the upper surface. Notwithstanding these important advantages, the pressing of rolled glass plates har'g plain surtaces was not practjcable prior to my invention. because ot certain dittculties, the cause ot which l have discovered to be attributable m-ny' to the fact that a hot body of nolten glass when placed on the rolling table heats and distorts different portious ot the table and of the inachine very unequally and thereby prevents the proper action of the pressing die over the entire surface ot the rolled sheet, and attributable also to the fact that a fiat pressing; die when brought in sndden contact with the' hot glass sheet, will chill and injure the surface of the sheet unless the die is niade duringthe operation of pressing. Having discovered the causes of these difiiculties I have invented means by which they can be etectually prevented as f0llows:-Instead ot making` the surfaces of the rolling table and die fiat rigid surfaces as heretotore, I make one or both ot theni coneave, so that when these paris on which the glass is supported and pressed are expanded by heat and are at their nor nal working temperature, they 'ill present substantially even parallel surtaces ,which will come into practically sinultaneous contact with the entire extent of the sheet to be pressed. It is only under these circunstances that the surtaces of a freshly rolled glas-s sheet can be properly pressed and finished, because the material of which such a sheet is composed is so viscous and offers such a resistance to edgewise flow that it is I and used in such manner as to prevent the impossible to alter to any eXtent the longitndina'l distribution of the metal in thesheet, The degree ot' concavity which itis i'iecessary to give to the table or the die sui-faces will vary sonewhat with the'relative size ot the various parts of the machine and the temperature at which the glass is worked. With a table (30)(90 inches the deg'ree of coneavity required in Operating on :lass at normal Working temperature is about one-fourth of an inch when the table is cold. To secure the proper finish and polish of the pressed surfaces and to prevent cracking` and checkingf" I employ a die whose surface is of such nature as to prevent anyrapid abstraction of heat from the rolled sheet during the operation of pressing'. This result maybe secured either by 'heating' the die to a temperature nearly equal to that of the senimolten ::lass sheet or by making the surface otthe die of a nou-conducting and highly polished nature, or by a combination of both of these means. A

The drawing shows means well suited to thepractice of my invention, but the apparatus may be modified in many otherways.

In the dnwings of Figs. l, 2 and 3, 2 is a table on which the body of plastic glass '7) to be Il'lOlClCd is placed. This table mounted upon standards 4, adaptdto be moved vertically, preterably by a pisten working' in a cylinder and intermediate connecting mechanism *consistingpf a pitnai 3 tically in bearings 44 and communicate to the table its vertical inotion. The cylinder is provided with suitable fiuid-supply conncctions, the rise of the table being etected by the admission of fluid and its descent being efl'ected by gravity. The position of the table when at its lowest point is (leterinined by an adjustable stop consisting, preferably, of an eccentric 7, which is adapted to be' engaged by and to stop part of the connccting nechanisin 6.

8 isa carriage on which is mounted a spreading roll 11 and a heavy press or backing plate 15 to which is attached a die plate 9. `he backing plate is provided with four lugs 16, which rest on adjustable nuts on the standards 17 and are backed yieldingly by springs whereby tension can be adjusted by nuts IS. The die plate is attached to and adjustable with respect to the carriage by bolts 19 and set-screws 20. Means are provided by which the die and hacking plate can be artificially heated to a high Initial temperature, and in the apparatus shown in Figs. 1 to 3 this is accomplished preferably by providing a 'series of combustion chanbers' 21 between the back of the dieand the plate into which gas and air are introduced by means of ppes 22, 23. Instead of this means of heating the die, I nay cnploy others such for example as those shown in Fig. 5, in which a net w ork of electric wires' are shown enbedded in a non-conducting mass ofinaterial in the backof the die-plate, or in any other 'approved 'nanner. The purpose of heating the die is to prevent the too'rapid transfer of beat-:from the glass to the die where the sheet of glass is being prcssed This result may be Secured without such high iuitial heating by facing the die, as in Fig. 5, with a non-conducting material or composition 24.

The spreading carriage is capable of longitudinal notion in order to move the spreading rol-l over the tabie and bring the hacking plate and die K .e surface of the rolled-out sheet For' this purpose I niay enpla in Figs. 1 and 2, in which positivcly driven carriage pinions 1:3 engage with stationary racks 14, the spreading roller being driven at the sa nc circuinferential speed by chain connections 12, or as in Fig. 5, I may' einploy positively driven stationary pinions 25 cngaging with racks 26 on the carriage 8. In this case the roller is revolved as it passes over the surface of the table by means of'a 'gea r 27 at one end engaging with a rack 28 on `the side of the table 2. The spreading roll' 11 is not rigidly boltcd to the car'riage 8, but is mounted in swingng hangers which perature of the table,

'lel so as to roll -out a sheet of' glass of uninisin shown hinged joints at 30. The roll is guided in its notion along the table and kept at a definite and predetermined distance above the surface ot' the same by ncans oftrangs or side strips 31 attachcd to the table.

In the construction shown in Figs. 1 and 2, the surface of the` table 2 is concaved or hollowed out at the center. The surface of the roll is similarly convex in longitudinal sectiomso that at the normal working teme., the temperature of the table just before the glass is rolled, the surfaces of roller and table are substantially parallel. 'In the apparatus shown in Fgs. and 6, both table and roller may go be fiat and straight, or one concave and the other convex as shown in Fig. 2. In either casethe object is to keep the surface of the table and the lower edge of the roller paralform thickness.

In Fig. 4 of the drawings I'show means which I may employ for mparting to the die a slight to and fre motion in theplane of the glass sheet while it is being pressed. 35 is a lever pivotally connected to the backing plate at 36 and connected by' links 37, 37' to fixed luge on the standards 17, 17. When an upward pressure and motion is imparted to the hacking plate and die by the vertically moving table, 2, the 'lever and links impart to the plate and die an edgewise to and fre moton over the sheet, andas the plate and die move down again under gravity and the action of the springs 10, a reverse motion results. The edgewise moticn of the plate is permitted by slotti ng the lugs 16, through which the standards pass and it is facilitated by placing steel balls or rollers between the washers 38, 38' inserted between the springs 10 and the adjusting nuts 18- on the top of the 'standards: Other equivalent devices may be. em loyed for giving an edgewise n'iotion to tiie die, the object of this edgewise motion being to secure more perfect pressingcontact between the surfaces of the sheet and smoothing out irregularities and defects that might escape the action of adirect up and down pressing action. In the apparatus shown' in Figs, 5 and 6, I cmploy for noving the table a multiplicity of cylinders 53 5', the pistons of which are attached directly to the* standards 4', 4:', 4'34'1; These standards slide through bearings in a. heavy iron base plate 4 5 the top'of which is planed flat and serves as a support for the rolling table 2 when the latter is in its lowest position. The-four corner standards are connected together by links and levers 6', 6' on shafts 40', so as to movetogether, the other intermediate standards 4",

4 and pistons may move independently.

In this form of apparatus the rolling` table is relatively thin and suificiently elastic to 1533' bend under the separate pressure of the standards 4', 4:". The eccentric 7' which regulates the relative separation of the table 2 and roller ll is in this case mounted in the hangers 29' in which the roller 11 is mounted.

The operation is as follows: The eccentric '7' is moved until the roll rests upon the side strips 31, 'which are adjusted to produ ce a sheet of the required thickness. The carriage S is moved back until the roll' is at one end of the table, as in F ig. 1, and a niass of plastic glass 9 is placed-thereon just in' front of the roller. The carriage 8 is then advanced soas to move the roll 11 forward over the .glass and spread it down on the table in a sheet of uniforin thickness the result being secured by forning the table and roll as already described. A further advance of the carriage noves the roll beyond the front end of the table, as in Fig. 5, and brings the die 9 over the sheet of rolled glass. In the meantirne the hot sheet of glass has heated the upper' surface of the' table 2' and caused it to bow upward to such an 'extent that the topsurface of the table 'and sheet ar'e now par-alle] with thesurface of the pressing die. Then by achnitti-ng fluid to the cyli'nder or cylinders 54 the table is raised and the surface of the rolled glass sheet is. brought into contact -with the pol- 'ished heated surface of the die `E) and by pressure" thereon is fiattened, conpactcd and gven a true'and highly pohshed surface.

:The table is then lowcred and the eccentric 7'-turned until the roller and table are separated sufliciently to enable the carri'age 8 to be retracted without the roller touching the finished pressed surface of the sheet and the latter is'renoved and placed in the kiln or 'annealing oven in the usual inanner. In order to secure-the best results the surface of the rolled glass sheet niust be brought into substantially sinulta'eous contact with theentire stu-face 'of the pressing die. 'To provide for this when the whole machine has reached its working temperature, I adjust the nuts 18 and the bolts and set screws and 20 'after the machine has reached the n'or'nal workng temperature already referrcd to, until"tho surface of the dieand table are as nearly. as possible parallel, before the rlass sheet is rolled out.

-A 'further automatic adjustinent of the die and table to parallelism is acconplishedby i its center relatively to its coruers, is compousated and elininated as already explained either by making` the surface of the table concave as in F 1 and 2, or by making the table sufiiciently thin as in Figs. 5 and G, tospring to the surface of the die under the independent action of the corncr staud ards 4" at' and the intermediate standard 4:, u

Instead of using a thin *table which will bend under the pressing' ai'tion of the standards so as to nale the top surface of the glass sheet conform to the entire surface ofthe die, I nay use a very thin flexible die surface as shown in Fig. 7, which is hung in a cavity in the hacking plate, by pins, so to bend readil y when the sheet. is pressed against it and conforn itself to the upper surface threof. In such case the lower table is made thick and rigid as in Figs. 1 and 2, but need not be made concave, as the bowing of the table under the heating action of the rolled sheet is conp'ensated for by the bending' of the top 'lexible die during the subscqucnt pressing operation. The die of Fig, 7 is kept hot by burning gas and air in the cavity between it and th'ebacking plate, or by insertingan electric hcater therein or by. any 'other suitable niea'is.

Many other forms of nechanisxn and various other means of operation n'iay be ein- .ployed-to acconiplish the results hcrein set,

forth, since Vhat l claim is:--

1 The heroin described improvement in the' art of making plate glass, which consists insubjecting'a free surface of a newly fornied and still plastic ::lass plate to prcssure and preventing` any substantial transfer of heat therefron 'to the pressing elenicnt, substantially as and for the purpose set fortln v 2. The herein described improvement in the art of making plate glass, which consists in applying prcssure to a free surface of a newly forned and still plastic plalc with said free surface and the face of the pressing element in substantial parallelisn, substantially as and for the purpose 3. The herein described improvement in the art-of making plate glass, which consists in applying pressure to a free surface of a newly forned and still plastic glass plate with said free surface and the face of the pressing element in substantial parallelisn and preventing any substantial transfer of heat fl'Oll'l the plate to the pressing element, substantially and for the purpose set forth. 4. The process'of finishing a plate of glass consisting in subjccting all parts of the free surface of the already formed and still plastic plate to substantially uniforin, simultaneous and r inomentary pressure, substan- I tially as and for the purpose set forth.

neous and nomentary pressure, and 'retarding the transfer of heat from the plate to the v pressure applying member, substantially as and for the purpose set forth.

6. The herein descrbed method, of makingglass .plates which consists in supporting a newly forned and still plastic plate of glass upon a table, and then applying pressure to that portion of the exposed or free part of the plate to be shapcd while plastic, and during the pressing operation preventing any substantial transfer of heat from said free or exposed surface of thc'plate to the pressing element in contact therewith, suh-..tantially as: and for the purpose set forth.

7. The .heroin described method, ofinaking glass -plates which consists in supporting a newly forned and still' plastic plate of class upon a table, and then applying pressure to the free or exposed surface thereot' throughout the area to he shapedwith the free or exposed surface of the glass and the face of the pressing element in substantial parallelism, substantially as and for the purpose set forth.

8. The heroin described method of making glass plates, which consists in first spreading nolten glass on a supporting surface having an initial contonr different from that of the surface to be in'parted to the glass, and utilizing the hoat-of the glass to change the contour of such surface to the desired form, and. then applying pressure to* the sheet and n'aintaining the forming surface of the' pressure-applying device in parallelisn with the surfaceof the prcviously for'ned sheet during the pressing opcration; substantially as described.

9. The herein described method of making glass plates, which consists in first spreading 'nolteu glass upon a supporting surface' having an initial contour different from th'at of the surface to he imparted to the glass, utilizing the heat of the glass to change the contour of such surface to the desired form, pressing the glassby pressure applied to the glass throughout substantiall'y its entire cross-section, and maintaining the forming surface of the pressure applying device in parallelism with the surface assumed by the sheet a the conclusion of the spreading operation; 'substantially as described..

10. The heren described method of making glass plates, which consists in spreading molten glass into sheet form on a surface 'which When cold is concave, utilizing the heart from the glass to expand such surface to' a plane form, and then pressing the lass and maintaining the forming surface of the molten glass into sheet form,

pressure-applying surface in parallelism with the surface assumed by the glass at the conpletou of the spreadmg operation,

substantially as described.

face to a plane form, pressing the' glass glass plates, which consists in spreading molten glass into sheet formon a metal sur face which When cold is concave, utilizing. the heat from the glass to expand said sur-' thereon over its entire area, and maintaining the t'cn'perature of the pressure app'lying medium suhciently hgh ,to prevent transfer of heat thereto from the glass; subi stantially as described.

13. The method hei-ein described of making glass plates, which consists in spreading molten glass into sheetform on a -concave surface of continuous curvature, and shaping the glass on said surface s'o that its upper and lower sui-faces will be substantially parallel, and then pressing the glass between pressing' elements whch are n substantal parallelism with the respective faces of glass; substantially as described.

14:. The method heroin described of maliing glass plates, which consists in spreading molten glass on a concave forming surface of continuous curvature, and then pressing the glass with a die, acting simultaneously throughout the area of the glass 'to be pressed and inparting to said die a temperature about equal to that of the glass sheet to be pressed; substantially as described. p

15. The method hei-ein described of making glass platcs, which consists in spreading nolten glass into sheet form, then pressing it and inparting to the pressing surface motion in the plane of the sheet; substantally as described.

10. The method heren described of making glass plates, which consists in spreading then pressing it and imparting to thepressing surface reciprocatin; moton in the plane of the sheet;

substantially as described. i

17. In the manufacture of glass shee'ts, the method which consists in first spreading molten glass into sheet form of at least the dimcnsions of the finished sheet, then applyng pressure smultaneously over the, er.- tire area of the sheet, and. mantainmg the a forming surface, means for spreading the glass thereon, and a pressing die arranged to apply pressure substantally simultaneously to the entire surface of the spread sheet, said die having means for preventing any substantial'transfer of heat from the glass to the die durng the pressing operation; substantially as described.

19. In apparatus for forming plate glass, -a table having a' forming surface', a coperatingspreading device, and a pressing element having a form-ing surface, the Centers of the cont-inuous curvature ofthe 'two sur- -faces being both locate& on the same side of their common plane; suhstantially as described.

20. In apparatus for forming plate glass, a supporting surface, means for spreacling molten glass into sheet form thereon, a .pressing die, and means for maintaining the forming surface of the pressing die in parallelism With the surface of the spread glass sheet; substantiallyas described."

21. In apparatus for forming plate glass, a supporting surface, means for spreacling molten glass thereon into sheet form, a pressing die having a forming surface,'and means for bending one of said surface-s to maintain parallelism between the surface of the spread sheet and the surface of the die; substantially as described.

:22. In apparatus for forming plate glass, a supporting surface, means for spreading molten glass t-hereon into sheet form; a pressing die, and means for bencli g said clie to change its forming surface; substantially as described.

23. In apparatus for makin glass plates,

a supporting surface, means or -spreacling molten glass thereon in sheet form, a pressing die, and means for imparting motion to said die in the plane of the sheet; substantially as described.

24. In apparatus for making glass plates, a supporting surface, means for spreading molten glass thereon in sheet form, a pressing die, and neans for imparting recipro cating motion to said die in the plane of the sheet; substantially as described 25. An apparatus for making glass plates having means for first forming molten glass into a plate by a spreading operation, and other means for a plying pressure to the exposed or free sur ace of the plate substantially simultaneously throughout its entire area and preventing any substantial transfer of heat therefrom to the pressing element during the pressing operation, substantially as and for the purpose set forth.

26. An apparatus for making glass plates having means for forming a mass of molten glassinto a plate, and other means for ap- ]'lying pressure to the free or exposed .surface of the plate throughout the area te be shaped and means for maintaining said surface and the face of the pressing element in substantial parallelism, substantially as .and for the purpose set forth.

27. An apparatus for making glass plates having means for forming a mass of molten glass into a plate, other means for applying pressure to the free or exposed surface of the plate means to maintain saicl surface' "and the face of the pressing element in sub- 

